Conventional handheld hairdryers, that incorporate an electrically-powered motorised fan to blow a current of cool or hot air in order to dry a person's hair, are well known. The fan draws ambient air into the body of the hairdryer and blows the current of air towards the hair to be dried. When hot air is to be blown, typically an electric heating element, incorporated within the body of the hairdryer, is used to heat the current of air before it leaves the hairdryer. Optionally, the hairdryer may be equipped with a concentrator nozzle attachment to intensify and direct the current of air, or a diffuser attachment to deliver the air more gently.
Although conventional hairdryers have been in use for many years, the inventors have observed and identified a number of shortcomings, as follows:
Conventional hairdryers can often be noisy, heavy and bulky. Furthermore, they can be awkward to use, and it can be difficult for a user (in particular a domestic user attending to their own hair) to achieve desired results, particularly in respect of styling the hair whilst drying it. For instance, a hairdryer will often be used simultaneously with a hairbrush or comb, or another piece of styling equipment, to style the hair during drying. The styling process may be, for example, to straighten the hair, or to provide “body and volume” to the hair (if necessary, preceded or succeeded by the application of styling products such as mousse, gel, wax, hairspray, etc.). Simultaneously maneuvering a hairdryer and a brush (or a comb, etc.) around the head can be awkward for the user, and often requires a degree of skill to achieve the desired results.
Moreover, it has been found that, with too gentle a flow of air it can take an unduly long time to dry the hair. Conversely, with too powerful a flow of air (e.g. using a concentrator nozzle), insufficient control can be provided during a styling operation.
Additionally, excessive use of hot air can result in damage to the hair, whereas the use of cool air can again result in the drying process taking an unduly long time.
Consequently there is a desire for hair drying apparatus that can be used to dry hair in a relatively quick manner, whilst also facilitating styling of the hair.
Furthermore, as illustrated in FIG. 13, the use of a conventional hairdryer to dry hair can be hampered by wet hair clinging together to form clumps, creating surface tension between the hair and making it hard for air from the hairdryer to pass though the hair (e.g. between individual hairs) to dry it. That is to say, clumps of wet hair have relatively high airflow resistance, impeding the drying process.
The clinging-together of wet hair into clumps can also give rise to further problems when the hair is subjected to hot air blown by a conventional hairdryer. In particular, the hair on the outside of a clump dries more quickly than the hair on the inside of the clump. Consequently, the hair on the outside of the clump can be damaged (e.g. scorched) by the hot air, whilst the hair on the inside of the clump can remain wet.
Blowing hot air using a conventional hairdryer can also be inefficient in respect of energy usage, as much of the energy in the hot air is lost into the atmosphere as waste heat. This is particularly the case if the hot air is deflected from a clump of wet hair, rather than being allowed to pass between hairs. This is illustrated in FIG. 13, in which a clump of wet hair 40 is shown in cross-section. An incident flow of hot air 56 is deflected by the clump of wet hair 40. Unbound water (as denoted by 51 in the enlargement) is shown on the surface of the individual hairs within the clump.
Furthermore, with such a clump, the “active” surface area of the hair (i.e. the surface area of the hair that is exposed to air, and from which evaporation of water can occur) is relatively small in comparison to the overall surface area of the constituent hairs added together, again giving rise to inefficiency in the drying process.
Indeed, more generally, conventional hairdryers have been found to be inefficient in respect of heat transfer and evaporation (i.e. low drying efficiency) and power consumption (i.e. low energy efficiency).
To address some of the above issues, hairdryers which blow more air and/or generate higher pressure air (e.g. so as to force the air through clumps of wet hair) have been considered as possible solutions, but this would likely lead to an increased size and weight of the hairdryer, increased operating noise, and greater inefficiency.
There is therefore a desire for an alternative approach to addressing at least some of the above issues.